<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    *{
      padding: 0;
      margin: 0;

    }
    li{
      list-style: none;
      width: 100px;
      box-sizing: border-box;
      border: 2px solid blue;
    }
    ul{
      display: flex;
      border: 1px solid red;
      width: 500px;
      justify-content: space-evenly;
    }
  </style>
</head>
<body>
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
  </ul>
</body>
</html>